Measuring the properties of dark energy and dark matter with strong gravitational lensing and stellar dynamics

我们的宇宙包含两种神秘的物质：暗能量和暗物质。需要暗物质来解释星系中恒星的轨道速度，而暗能量解释了宇宙膨胀加速的惊人观察。在这个项目中，我们将结合哈勃空间望远镜对强引力透镜的观测和甚大望远镜对恒星轨道特性的观测来约束暗物质和暗能量的特性。引力透镜是由于大质量星系周围时空的扭曲而产生的。当来自背景星系的光经过前景星系时，其路径会发生偏转，在某些情况下，这种偏转大到足以观察到背景源的多个图像。这些罕见的排列被称为强透镜，图像之间的分离对透镜星系中的暗物质和我们与光源之间的暗能量很敏感。然而，这些性质是简并的，只有结合外部数据，我们才能解开暗物质、暗能量和引力的影响。我们将利用透镜星系中恒星的轨道特性来打破这种简并：随着星系质量的增加，恒星的轨道速度会更快。

Our Universe contains two mysterious substances: dark energy and dark matter. Dark matter isneeded to explain the orbital speeds of stars within galaxies, and dark energy explains the surprisingobservation that the Universe's expansion is speeding up. In this project we will combine HubbleSpace Telescope observations of strong gravitational lensing and Very Large Telescope observationsof the orbital properties of stars to constrain the properties of both dark matter and dark energy.Gravitational lensing occurs due to the warping of space time around massive galaxies. As light froma background galaxy pass by a foreground galaxy its path is deflected, and in some cases thedeflection is large enough that multiple images of the background source is observed. These rarealignments are called strong lenses and the separation between the images is sensitive to dark matterin the lensing galaxy and the dark energy between us and the source. However these properties aredegenerate, and only by combining with external data can we disentangle the effects of dark matter,dark energy and gravity. We will use the orbital properties of stars within the lens galaxy to break thisdegeneracy: as the mass of the galaxy increases, the stars orbit faster.